Hello @Harentsoa RANDRIAMAHOLIMANANA ,
standard authentication is now disabled in all clients. Before December 31, 2022, you could re-enable the affected protocols if users and apps in your tenant could not connect. Now no one (you or Microsoft Support) can re-enable Basic Authentication in your tenant. You can find more information on setting basic authentication in Exchange Online in the following article.
Basic Authentication Deprecation in Exchange Online - Time's Up: https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-deprecation-in-exchange-online-time-s-up/ba-p/3695312
The "SMTP" protocol is not affected by this and can still be used. However, you must ensure that SMTP authentication is activated for the mailbox used. SMTP AUTH is disabled for organizations created after January 2020, but can be enabled per mailbox. You can find out how this works in the following article.
Enable or disable authenticated client SMTP submission (SMTP AUTH) in Exchange Online: https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission
To configure your device or application, connect directly to Microsoft 365 or Office 365 using the SMTP AUTH client delivery endpoint smtp.office365.com. Each device or application must be able to authenticate with Microsoft 365 or Office 365. The e-mail address of the account used for authentication with Microsoft 365 or Office 365 is displayed as the sender of the messages from the device or application.
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